Overtime UI cleanup

[Carla-Moz]

This PR cleans up several Compare Overtime UI bugs addressed in PR #674

• [x] remove the extra margin on labels
• [x] fix the the width of the search input and spacing between labels and dropdowns
• [x] fix dark mode colors and icons (use svg for icon instead of github url)
• [x] use visibility hidden or visible to display or hide the edit button

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.70%. Comparing base (05ff980) to head (dc51776).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## beta #682 +/- ## ========================================== + Coverage 91.66% 91.70% +0.03% ========================================== Files 71 71 Lines 1728 1735 +7 Branches 323 329 +6 ========================================== + Hits 1584 1591 +7 Misses 114 114 Partials 30 30 ```

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